The anion surface-active agent having the per-fluorocarbon chain as a main component is used as an indispensable material of a production process in many fields, such as an emulsion polymerization process of PTFE (poly-tetra-fluoro-ethylene), and a production process of an electronic parts industry. Moreover, said anion surface-active agent is also widely used as a material, which are various paints, a coating agent, and a fire-extinguishing agent, etc. However, in these production processes, the above-mentioned anion surface-active agent has been used as a dilute solution, such as several % to 0.01% by weight, so that the efficient fixing and recovering said anion on an industrial scale has been difficult. Moreover, the problem of this fixing and recovering has not been considered in general because this solution is dilute. Furthermore, the fluorine compound, such as said anion surface-active agent, is a hard material to be processed by the activated sludge processing, which has been widely used as a wastewater processing. However, a harmony of chemical materials to environment or ecosystem is required strongly in recent years, and, also about this fluorine compound, it is started that the necessity of the technology about the closing system by fixing, recovering and reproducing is recognized strongly.
According to the fixing and recovering of this anion surface-active agent, the technology using the layered double hydroxide has been examined to be in practical use about a phosphate anion or an organic anion, as a scavenger or a removal agent of anions. However, about molecular anion having the per-fluorocarbon chain as a main component, such examinations have not been done previously. In addition, as a conventional technology, it is known that the process, in which an ammonium salt of fluoroalkane acid is extracted to recover by using an organic solvent, such as dichloro-methane or trichloro-methane, was proposed (Japanese Patent Raid Open No. Shou 61-215346), but this process uses an organic solvent containing chlorine, so that it is not enough for reducing the burden to environment.
In addition, the inventors have already reported the layered double hydroxide having anion between layers (Zn2Al(OH)6C7F15CO2) for the purpose of a material synthesis (the 76th spring annual meeting of the Chemical Society of Japan), about a high concentration aqueous solution of per-fluoro-octanoic acid ammonium, i.e., about 8.6% by weight. However, this report was not for the purpose of fixing and recovering of the anion like this invention, about the solution having the wide concentration range including the dilute solution of 0.1% by weight. Therefore, the process about fixing of such fluorine compound has not been reported yet.